App Crashes while connecting activities

Question

Am going through the tutorial in the below link to have a simple Android App with more than one activities.

https://developer.android.com/training/basics/firstapp/starting-activity.html

I have followed the steps as specified in the android tutorial, I run into a NullPointer Exception on the EditText Widget,

java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference

Below is my MainActivity.java where the exception as editText returns Null though I assume I have wired it in the right way,

public class MainActivity extends AppCompatActivity {
public final static String EXTRA_MESSAGE = "com.my.application.message";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

public void sendMessage(View view){
    Intent intent = new Intent( this , DisplayMessageActivity.class);
    EditText editText;
    editText = (EditText) view.findViewById(R.id.edit_message);

    System.out.println("the values is "+ editText);

    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE,message);
    startActivity(intent);

   }
}

And below is the activity_main.xml ,

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="horizontal">
 <EditText android:id="@+id/edit_message"
     android:layout_width="0dp"
     android:layout_weight="1"
     android:layout_height="wrap_content"
     android:hint="@string/edit_message" />
 <Button
     android:id="@+id/button"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="@string/do_send"
     android:onClick="sendMessage"/>
</LinearLayout>

Any pointers here to get past this ?

`EditText` is in Activity layout instead of in `view` (which is instance of clicked View(in your case it is Button)), so just access it without `view` like :`editText = (EditText)findViewById(R.id.edit_message);` — ρяσѕρєя K, Dec 27 '16 at 16:10
where did you call your "sendMessage" and don't use "view." , initialise without this. — Rakshit Nawani, Dec 27 '16 at 16:12
@Rotwang - This question isn't around the NullPointer exception in general but to the activity scenario mentioned here. So it isn't a duplicate question or at least isn't the duplicate of question tagged . — Ashwin Sridhar, Dec 27 '16 at 17:06
@AshwinSridhar Nooooo... What is not clear in `I run into a NullPointer Exception on the EditText Widget`? — Phantômaxx, Dec 27 '16 at 17:16

score 2 · Answer 1 · answered Dec 27 '16 at 16:17

2

on line of click :

   editText = (EditText) view.findViewById(R.id.edit_message);

"view" is that button. and by using view.findViewById, you are trying to find required view in that button (which is not parent of you EditText). So you should try following ways :

Direct :

editText = (EditText) findViewById(R.id.edit_message);

here findViewById will try to find id in current Activity.

using parentView :

editText = (EditText) (view.getParent().findViewById(R.id.edit_message));

here your button's parent is EditText's parent, so it will find you EditText by this code also.

answered Dec 27 '16 at 16:17

NehaK

2,639
1
15
31

1

Thank you NehaK , the explanation is very crisp and to the point. – Ashwin Sridhar Dec 27 '16 at 16:26
welcome!..please my answer as right. – NehaK Dec 27 '16 at 16:27

score 0 · Answer 2 · answered Dec 27 '16 at 16:13

0

Your function is in an Activity so you don't need to do view.findViewById(). Instead, simply do the following :

EditText editText;
editText = (EditText) findViewById(R.id.edit_message);

answered Dec 27 '16 at 16:13

Ankur Aggarwal

2,210
2
34
39

score 0 · Answer 3 · answered Dec 27 '16 at 16:16

NullPoint address to those objects which has null values, put proper id and code:

public class MainActivity extends AppCompatActivity {
public final static String EXTRA_MESSAGE = "com.my.application.message";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}


public void sendMessage(View view){
    Intent intent = new Intent( this , DisplayMessageActivity.class);
    EditText editText;
    editText = (EditText) findViewById(R.id.edit_message); //here

    System.out.println("the values is "+ editText);

    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE,message);
    startActivity(intent);

   }
}

score 0 · Answer 4 · edited Dec 27 '16 at 16:51

0

You're trying to find an EditText from the clicked button

editText = (EditText) view.findViewById(R.id.edit_message);

You have to find it from the Activity

editText = (EditText) findViewById(R.id.edit_message);

Read that tutorial again, you'll spot the difference

edited Dec 27 '16 at 16:51

Charuක

12,953
5
50
88

answered Dec 27 '16 at 16:16

OneCricketeer

179,855
19
132
245

score 0 · Answer 5 · answered Dec 27 '16 at 16:22

As advice, I would first seek that it is not null or empty.

       if(editText != null && !editText.getText.toString.equals("")) {
            ...
       }

After I would follow the advice of ρяσѕρєя K:

EditText is in Activity layout instead of in view (which is instance of clicked View(in your case it is Button)), so just access it without view like :editText = (EditText)findViewById(R.id.edit_message);

App Crashes while connecting activities

5 Answers5